Select the correct indirect form of the given sentence.

Mohan said to' Radha, "Who were you speaking to over the phone?"

Mohan asked Radha who she had been speaking to over the phone.

The correct indirect form of the given sentence is:

Mohan asked Radha who she had been speaking to over the phone.

The other options are incorrect for the following reasons:

• Mohan ask Radha who she have been speaking to over the phone. The verb "have" should be in the past perfect tense, "had".
• Mohan asked Radha who she was speaks to over the phone. The verb "speaks" should be in the present participle tense, "speaking".
• Mohan asks Radha who she had been speaking at the phone. The preposition "at" should be "to".